Land and oceans
White roofs could cool cities: study
Enzyme crystal helps crack HIV puzzle
Sugar sweetens decision making
Twilight zone secrets revealed
Astronomers spot asteroid collision
Algae master quantum mechanics
Protein 'ushers' key to beating malaria
Researchers spin artificial bee silk
New view of Pluto increases mystery
Cell's power packs came from within
Antarctic snow linked to WA dry
Termites inspire hydrophobic materials
Study shows why it's scary to lose money
Soil impact underestimated: climate study
Lack of oxygen forced fish's first breath
Harder Sudoku puzzles on the way?
Weed genes could help feed the world
Logging makes forests more flammable: study
Food crisis looms warn scientists
Tiny sensors track 'lost' objects
'Climategate' university orders review
'Plumbing' key to flowering success
New twist on solar cell design
Scientists set new temperature record
Chile quake tops Haiti, but less deadly
The Chile earthquake released nearly 1,000 times more energy than the one that devastated Haiti in January, but left 200 times fewer fatalities.

While rescuers are still searching through the rubble, experts says many factors explain the difference between the approximately 700 dead so far in Chile while the grim tally in Haiti has topped 220,000.

An earthquake's magnitude reflects the amount of seismic energy released at its epicentre, usually the meeting point of tectonic plates pushing up against or pulling away from each other.

The Haiti quake, which struck on January 12, measured 7.0 in magnitude, while the one in Chile, at 8.8, was nearly two orders of magnitude greater.

Each notch on the scale represents a 10-fold increase in amplitude, or the degree of shaking of the ground, and a more than 30-fold jump in the amount of energy released.

"But there is no direct link between magnitude and its deadliness or level of destruction of human habitat," says Robin Lacassin, a seismologist at the Institut Physique de Globe in Paris.
Quakes in unpopulated areas

Some 15 to 20 quakes every year top magnitude 7.0, but most of them go unnoticed except by scientists because they occur in the ocean or unpopulated areas.

Both recent quakes occurred near large cities, so other factors account for the difference.

"The earthquake near Port au Prince was very shallow, only about 15 kilometres below the surface," compared to about 35 kilometres below the ocean floor for Chile, Lacassin says.

But proximity alone did not account for the massive destruction of huge loss of life in January, he and other experts point out.

"The quality of construction and building codes in Haiti were obviously not as strong as those in Chile," says Dr David Galloway, a seismologist at the British Geological Survey.

The region along the western coast of South America has been hit several times before by major quakes, including the largest on record - a monster in 1960 measuring 9.5 on the Richter Scale - very nearby.

"Chile knows earthquakes. Their codes are more stringent," says Galloway.

It does not help that Haiti is beset by deep poverty and a history of dysfunctional governance.
Construction critical

The critical role of construction quality is highlighted by comparing the Haiti quake with a similar one in Kobe, Japan in 1995.

"The Kobe earthquake was 6.9 on the Richter Scale, was almost as superficial -- less than 20 kilometres under the surface -- and very near the epicentre," says Lacassin.

It was also the same kind of so-called slip-strike fault in which two plates rub past each other.

The death toll in Kobe was just over 5,000, considered shockingly high at the time because the city had been built to withstand intense ground shaking, but still only a fraction of the Haiti toll.

There is also an element of luck, depending on what time of day the pressure that has built up within Earth's surface layer, over decades or centuries, finally gives way.

"In Chile, a lot of car parks collapsed, but there was nobody in them because it was the middle of the night," notes Galloway.

Had the shaking started as people arrived at work or headed home, the tolls would be far higher, he says.

Horny mother beetles fight for dung
Light-speed computing one step closer
Small asteroids 'just lumps of gravel'
Gene study reveals diverse gut zoo
Dinosaur extinction caused by asteroid: study
Study finds methane bubbling from Arctic
New view reveals Mars' icy history
Some nano-sunscreens 'come at a cost'
Dust bunnies could harbour toxic load
Aphid genome reveals its 'Achilles heel'
Tailored diet may slow down DNA damage
Scientist probe ballistic chameleon tongue
Moa eggshells yield ancient DNA
Toothbrush tech helps buses go green
Gene protects some Tassie devils from tumour
Smaller fish cope better with acidic water
Lunar mirror mystery solved
Parents give fewer bad genes than thought
Women on pill may live longer
Antarctic winds affect key ocean layer
Researchers uncover thalidomide mystery
Boost for evidence of early ocean
Ocean geoengineering may prove lethal
People leave unique 'germ print'
Rogue star on collision course
Butterflies 'fly early as planet warms'
Glaucoma may start in the brain
Tools push back dates for humans on Flores
Stem cell capsules to target broken bones
Ecstasy damages complex memory: study
Earliest animals flexed their muscles
Insomnia may shrink the brain: study
Experts call for 'resilience thinking'
Tutu's DNA could point to medical cures
Humble algae key to whale evolution
Happiness linked to healthy heart
Fewer cyclones, but more intense: study
Cosmic candles result of colliding stars
Flightless mosquitoes may curb dengue
Childhood poverty may leave its mark
Cautious response to technology strategy
Nanowire RAM to make ever-ready computers
Are non-smokers smarter than smokers?
There's iron in them thar Martian hills
'Shell Crusher' shark swam ancient oceans
Nanotechnology may tap into your mind
Small dogs originated in the Middle East
Brain 'hears' sound of silence
Swimmers 'may not understand' tsunami risk
Altruism surfaces on slow-sinking ship
Chile quake tops Haiti, but less deadly
Weedkiller 'makes boy frogs lay eggs'
Visit Statistics